Telephone system



- Filed March 20. 1930 5 Sheets-Sheet l Inuen or Charles L. PETE F's"Feb. 16; j 1932. c. 1.. PETERS TELEPHONE SYSTEM Filed March 20, 1930 5ShBQLS-Sheet Inusn 01'' Charles L. FEE-"5 Feb. 16, 1932. c PETERS1,845,983

TELEPHONE SYSTEM Filed March 20. 1930 5 Sheets-Sheet 3 Irma? Charles L.PETEE C. L. PETERS SYSTEM Feb. 16, 1932.

TELEPHONE Filed March 20. 1930 5 Sheets-Sheet 4 Inuen or Charles L. PEare Feb. 16, 1932. c. L. PETERS 1,845,983

TELEPHONE SYS TEM Filed March 20. 1930 s Sheets-Sheet s Patented Feb.16, 1932 c UNITED STATES PATENT OFFICE.

CHARLES LEONARD PETERS, 01 LONDON, ENGLAND, ASSI GNOR TO SItEMENSBROTHERS 86 COMPANY, LIMITED, OF LONDON, ENGLAND TELEPHONE SYSTEMApplication filed March 20, 1930, Serial No. 437,544, and in GreatBritain March 26, 1929.

The present invention relates to automatic and semiautomatic telephonesystems and more particularlyto a system employing register controllersfor recordingthe numbers dialled by subscribers and controllingselection oi the desired line and for other operations connected withthe setting up of a call.

The invention though capable of wider applications is especiallysuitable for use in connection with small unattended exchanges and meetsthe demand for special services. The system shown herein may beconsidered as an improvement on the system shown in the patent to D. A.Christian, 1,738,564, granted December 10, 1929. y

it is provided in the present invention that a digit recording switch inthe register controller or an equivalent of such switch e. g. a relayset hereinafter called a digit switch has more contact positions thanthose corresponding to the digits employed in the sub scriber numberingscheme, and the surplus contact positions are employed for specialoperations to be controlled by a distant operator. Such specialoperations include trunk oil'ering whereby the entry into an engagedline must be secured, getting access to a tone circuit which cansignifya normal or abnormal condition at the exchange and controllingthe starting or stopping of battery charging equipment.

The special operations are initiated by the operator dialling a digit ordigits which sets the digit switch onto the appropriate contact where anappropriate relay may be operated.

A further feature of the invention is that to prevent any interferenceby ordinary subscribers, the relays concerned with the specialoperations are only connected to the switch contacts when the registercontroller is taken into use by an operator. To this end it may bearranged that whilst the incoming end of the junction from the operatorsposition has line equipment such as is provided for a subscribers line,certain auxiliary equipment is provided whereby a relay is operated inthe register controller and connects up therelays concerned with thespecial operations. If connections are made tothe surplus contactswhereby an ordinary subscriber may by dialling special digits bringaboutcertain operations such as the setting up of a connection to themanual operator or a throw-out of ex change apparatus on inter-partycalls, these special digitsmay be used by an operator for other purposesby providing for a change of connections when the relay operated fromthe auxiliary equipment is energized.

Likewise if provision is made whereby a signalis given to a subscriberif he dials a digit not in the range of subscribers mom hers, thesurplus contacts involved or any of them may be used for specialoperations controlled by the operator.

In connection with trunkofi'ering it may be provided that the operatordials a special first digittobring about circuit changes in the registercontroller of which allow of breaking into an existing connection.

In this case we may arrange that the first digit switchof the registercontroller after being operated by the special first digit causes adiscriminating relay to operateandthen returns to normal to be operatedsubsequently by the first digit of the subscribers number.

.In a system in which the testing of a required subscribers line and thesubsequent operations are effected from the register controller, thediscriminating relay may control circuit for switching through theoperator to the required subscribers line independently of whether theline is free orbusy.

WVhere the. register controller includes an additional switch orswitches which are 0perated to select a ringing circuit for party linecalls, one of the switches may also be used to select circuits for saybattery charging control under the control of impulses sent by theoperator, the first digit sent having operated a special operation relaywhich brings the ringing circuit selecting switch into the impulsingcircuit.

Other features of the invention will become apparent upon a furtherperusal of the specification.

Reference will now be had to the accompanying drawings which show by wayof (3X ample one anethodjof carryingout the invention. The drawings showcircuits in a small unattended automatic telephone exthe registercontroller with it.

' exchange' apparatusin setting up a call change in which provision ismade for local calls between individual line subscribers, calls to andfrom party line subscribers, and calls over junctions between theautomatic exchange and an operators position at a main exchange. Besidesthe handling of ordinary subscriber calls, the operator at the mainexchange is able to set up trunk calls to a subscriber who is alreadyengaged in alocal call, and to control the chargingiof the battery atthe automatic exchange and to ascertain if any faults exist at theautomatic exchange and if so the class of fault.

For the purpose of the following description the drawings should bearranged with Figs. 1, 2 and'8 on the left, Fig. 4; to the right ofFigs. 2 and 3', and Figs. 5 and 6 beneath one another below Fig. 4; Fig.7 should be placed onthe right of Fig. 4.

' Fig. 1 shows equipment connected in between-the line circuit shown inFig. 2 and the terminals on the main distributing frame connected toa'jun'ction to the main exchange which controls the special servicesprovided for. The line circuit shown in Fig. 2 may be'usedin connectionwith subscribers" lines or with junction lines, the straps shown on theleft of the figure being removed when the circuit is connected toequipment as'shown in Fig. 1. 'Fig. 3 shows'an assigner forallotting,-for use on'a call,'one of two register controllers whichconnects itself to-an idle connecting circuit and receives the dialledimpulses, sets the connector of the connecting circuit on to contactsassociated with the required line and 'performsany special servdetaileddescription of the circuits involved and of those concerned with theperformance of the special services available toan oper- 'ator' atthe'main exchange. i

On theinitiation of a call, the line relay- LA operatesand closes acircuit to the 'as-' signer AG which then assigns a' free registercontroller to deal with the *call. 'Ahunting switch CGF is set inmotio'nto connect'the' "ceeds' to search for the calling line whi'ch' registercontroller with a free connecting circuitjGC, the call finder CFo'f'which pro when foun'd is connected overthe' banks of theswitch CCFto the register controller. In the register controller arethree digitswitches DT, DU and DA on which the digits of the subscribers number arerecorded. The exchange in the present example is arranged for 50 lines,consequently individual subscribers numbers will comprise two digitsonly and these are recorded on' switches DT and DU. DA records the digitwhich designates a particular party on a party line and provides for theapplication of the appropri ate ringing code,[the control of the coderinging being effected I by switch DB.

7 Switch DA is also employed in connection with the control of thecharging of the automatic exchangebattery; Switches DT, DU, DA are25-point. switches, and as regards switches D1 and DU, the operativecontacts in the first part of their banks are connected symmetrically to"contacts in the latter part of their banks. Only some of these contactsare requiredfor subscribers numbers, the remainder being used forspecial purposes. For instance in the arrangement shown contacts 2to 6from the normal in the banks of switch DT areallotted tosubscribers-numbers; contacts 1 and 8 are wired for dealing with deadnumber calls;'fcontact .7 is wired for the release o'f'theexcha-ngeapparatus on interparty calls, in which case, before the calling subscriber useshis hand generator to call the wanted party on thesame line, he dials the digit 7 to effect the release of the seizedexchange apparatus. Contact 9 of switch DT is wired for faultsupervisory purposes and forfthe control of the battery chargewhile-contact 10 is used for outgoing junction calls from a subscriberand for the setting'up of preferred calls to a busy line by an operatorat a distant exchange. This latter operation and those giving thespecial services provided for over Contact 9 can only take p'lace'whe'nthe 'call is initiated ato'r at a distant exchange astherelevantcircuits depend for their operation on the energization of relay J C'which canonly. occur when the register controller is connected over thejunction equipment jumpered in between the main distributing frame andthe line circuit. V

The switchCCF besides hunting for a free connecting circuit acts as asequence switch with three positions. In the first position an idle'connecting circuit isseized an'dits call finder'ro'tated in search ofthe calling line.- When 'thishas been found theswitch CGF is stepped toits second position and the dialled digits are received in the registercontroller on the digit switches; Vhen all the digits have been-receivedthe wanted" line is'marked in the bank' of the connector CS which isstarted in search of the marked line. 'The line when found is tested toascertain whether it is free or busy andrif' free is marked engagedagainst. other call finders and connectors. The switch GCF'is thenstepped to its third position I which ringby an opering current isconnected to the line from the scribed. As regards Fig. 2 the strapsbetween the terminals will remain as shown, the meter M being connectedto wire (Z. VV1res a; and h are connected to the subscribers line on themain distributing framehen a subscriber lift-s his receiver to make acall his line is looped and line relay LA operates over the loop. Atcontact Zcl the test-in circuit of the connector GS (Fig. 4) is openedthereby marking the line engaged in the connector multiple. This can beseen by reference to Fig. 7. In its front position contact Zal connectsbattery over cut-otl relay CO and baclr contact p02 to the test bankcontact of the call finder CF (Fig. l) to mark the line as calling inthe call finder banks. At contact lei a circuit is closed for relay ASin the assigner. Relay PG is included in this circuit but does notoperate owing to the resistance of the circuit.

If the assigncr circuits are in the position shown a circuit for relayAA is closed from battery over contact thi winding 1 of relay AA, hackcontacts 661, col, contact cal to earth. Itelay AA operates and atcontact cad closes a circuit from battery over winding I ot' relay CC,back contact 5M, front contact (Add, contact cal to earth. Relay CCoperates and at the front position of its make-before breal: contactcol, connects earth over contact cs1, winding II of relay CC and frontcontact (m3 to the starting wire oi a register controller, which wire iseither connected to battery over starting relay EST it the registercontroller is free, or is disconnected it the register controller isengaged. If the register controller is free, relay CC holds in serieswith relay ST. Relay BB operates by means of its winding I in serieswith. winding I of relay AA and contact arr/2 when the short circuitacross it is removed by the changing over of contact cal and openscontact 5122. Contact 5711 changes over leaving the two re laysdependent on relay AA. If the register controller assigned over thefront of contact (m3 is busy, relay CC does not hold and on therestoration of contact 001, winding II of relay BB energizes overcontacts M3, bbl, cal and asl. At the same time winding II of relay AAis energized in parallel with winding II of relay BB and as the windingsof AA are arranged diflerentially, the latter relay releases and contactcal and M42 opening, leave relay BB dependent on relay CC for itscontinued energization. Contact ace falling back closes a circuit forwinding I of relay CC over the front of contact Z1224 and winding II ofrelay CC is connected over back contact m3 to the other registercontroller, two register controllers being provided. When contact 001changes over relay BB rcleases and opens the circuit of winding I ofrelay CC leaving that relay dependent onthe condition found on the wireconnected to the back oi contact aa3. It the register con-' troller, thestarting relay of which is connected to this wire is free, relay CGcontinues to hold otherwise it releases and relay AA re-operates to testthe first-mentioned starting circuit again.

Assuming that one of the register control lers is free, relay SToperates in a circuit from battery over the relay winding, contact #1 2of the ring tripping relay 'IR, contacts 91, 6Z7, wiper D313 of the tensdigit switch in its normal position, contact (m3, winding II of relayCC, contacts 001 and cal to earth.

Switch CCF besides connecting the register controller to the connectingcircuit acts as a sequence switch for the carrying out of variousoperations "through the connecting circuit under the control ofapparatus situated in the register controller. For this purpose theswitch has three positions associated with a connecting circuit. In thefirst, the test for a free connecting circuit is made, the call tinderset huntin for the calling line and the line extended to the registercontroller. In the second, the dialled impulses are received and theconnector set on to the wanted line, and in the third, the called lineis rung, and when the subscriber replies to the call, the callingsubscribers meter is operated. The switch remains in the j ird positionafter use in which position t e test circuit over wiper 7 of switch CCFis either openor earthed. (in the closure of contact $252 a circuit isclosed for magnet DF over an interrupter and the switch is stepped onceto the first position associated with another connecting circuit. Ifthis circuit is busy .the test relay T associated with switch GCF .willeither be short circuited over Wiper 7 and contact Q11 in the otherregister controller or the circuit of relay T will be open at contactno? in the engaged connecting circuit. Switch CCF is stepped by theinterrupter until a free circuit is found. Whilst in the second andthird positions associated with an engaged connecting circuit, relay Twill be prevented from operating in a similar manner to that in thefirst position.

The circuit of relay '1 being prepared at contact stl the relay operateswhen free contacts are encountered over wiper 7 inits first 5 nection isnot completed within a prescribed test relay T to reduce the potentialon the,

period. Contact st5 closes a holding circuit for relay ST againstoperation of relay Q.

When relay T operates. contact 61 short circuits the high resistancewinding I of the testing contact to mark the connecting circuit engaged.Winding I of relay Q, is energized over contact 62 and the relayoperates slowly. Contactt3 changes over to prepare the circuit of magnetDF for stepping the switch to its second position. Contact Z4 preparesthe circuit of the callfinder test relay TC, contact 65 prepares acircuit. for

relay B and contact t6 operates magnet DC of.

the connector. Magnets DF, DA and DB are all of the reverse-drive type,i.; e., they step their switches on the release of their armatures.-Relay Q operating contact 94 opens the circuit of magnet DC and theconnector takes one step.

Contact 91 opens in the operating circuit of relay ST but this relay isheld over contact st5. A circuit is now closedzfrom earth overinterrupter contacts g3, 55, 2, wiper 5 of switch CCF in its firstposition and contact 1603, magnet DD of the call finder to battery. Thecall finder CF is stepped in searth of the calling line unless ithappens to be standing on contacts connected therewith at the time. Whenthe calling line contacts are reached, relay TC operates in a circuitfrom earth over contact 254, wiper 2 of switch CCF, its winding I, wiperC of the call finder, contacts p92, Zal in the line circuit, relay CO tobattery. Contact Z02 changes over to connect Winding II of relay TC in aholding circuit in series with winding II of relay T and in parallelwith relay S. Contact tel connects earth to the. call finder test wiperto mark the line engaged and to operate relay CO which looks up over itscontact 001. Contacts 002 and 003 disconnect line relay LA and on itsrelease, relay PG. operates over contacts M2 and 004 but without effect.Contact Z03 opens the call finder magnet circuit and contacts 604, andtc5 connect the incoming speaking wires to the bank contacts of wipers 1and 3 of CCF. Relay B having operated, the windings I and II of relay Aare connected to wipers 1 and3, and that relay operates.

Contact [)6 opens a point in the interrupter circuit tor ma'gnet DF andcontact 64 closing operates this magnet over front contact t3. Contact57 operates the slow releasing dialling relay D via wiper DT2 and itsnormal bank contact. Relay A operates over the subscribers loop in thecircuit traced and at contact a2 operates relay Va j Relay Voperating-contact @1- short circuits relay T which thereupon releasesandat-contact t8 opens the circuit of magnet DF causing it to release andstep. switch CCF to its second position. Relay-Q is released atcontactt2 and contact 91' closes in the operating circuit of relay ST,which circuit however, is

7 now open at contact d7 which released relay ST when relay D operated.The register controller cannot now be assigned by an as signer as thecircuit over contact m3 and winding II of relay CC is open. Othereffects of the operation of relay V are the retention of the circuit ofrelayTP over contact e3, the preparation of a circuit for relay SA atcontact '02, the preparation of a hold-' 'ing circuit during impulsingfor relay D at contact 04: and of an impulsing circuit for the digitswitch magnets DT and DU at contact '06. Contact 125 closes a holdingcircuit for relay B. Contacts (Z2 and (Z3 opens points inthe circuits ofslowreleasing relays G and.

E, contact 614 prepares the impulsing circuit of the digit switchmagnets, and contacts d5- opens the circuit over wiper DT6.

On the operation of relay B a dialling signal is applied to the lineover wire DS, con-.

tact t05, normal bank contact and wiper DT L, condenser, contact 62,wiper 1 otCCF and contact to l and the subscriber commences todial thenumber of the wanted subscriber which, except in the case of a partyline sub.- scriber, comprises two digits. The numbers 20 to 69 areallotted to subscribers in the pres-- repeated over contacts (12, 16,(Z4 and g-ito magnet DT. Switch DT is stepped in accordance with thenumber of impulses received and its wipers DT3 and DT6 are brought toone of the contacts 2-to 6, counting the normal contact as O. Theoperating circuit of relay D is-opened at the end of the first impulseat wiper DTZ and the relay is then dependent on back contact'al for itscontinued energization. The diallingsignal is cut cit at wiper DT4' andthe starting circuit is further opened at wiper DT5. At the end of theimpulse train relay A remains steadily operated and relay D releases.Relay G now operates from earth over contact 67, wiper and commonedcontacts 1 to 10 in the bank of wiper DT2, contacts 81' and d2, andlocks up over contact g1. Contact g substitutes magnet DU for magnet DTfor the reception of the units digit, A circuit is also closed fromcircuit. Contact 73 closes a point-in the cir-.

cuit of the test rclayP for testing the called line, contact 95 opens apoint in the busy signal circuit and contact 6 prepares a circuit foroperatin inagnet DF. The units train of impulses is now dialled and isrepeated to magnet DU which steps the switch in accordance with thenumber of impulses .received and wipers DIE- are brought to contactsconnected to the marking bank as sociated with wiper D of the connector.

lit the end of the units train of impulses, relay D releases and acircuit is closed from earth over contacts at, al, g2, n1, jtl, WiperDU? and common contacts, contacts (Z3, Z4, contact on the other registercontroller available over the assigner via wires 6, contact r45, relayIll to battery. 9

It may here be noted that should the second register controller be inuse at this time, confusion in the banks of the connectors might occurshould the banks be marked over contact at and wiper DT3 and one of thebanks of switch DU this time. It the calledline marked by the secondregister controller has not yet been found, its relay E shown in dottedlines at E at the bottom of Fig. 6 would be operated and its contactcorresponding to e5 would be open thereby delaying operation of relay E.

As soon as the other calling line is found and tested relay E releasesand its contact 65 completes the circuits oi relay E which thereuponoperates and locks up over contact (21 independei'itly of contact a1.Contact 65 opens to prevent operation of relay E in the other registercontroller at this time. Contact e2 closes a circuit from earth over theinterrupter, contacts 83, e2, Z3, Z55, wiper r of CCF, magnet DC of theconnector to battery and the connector wipers are stepped round thebanlr.

Contact a l marks the called line in the bank of wiper D of theconnector, the line marked depending on the position of the wipers ofswitches DT and DU, and contact 63 prepares a circuit for relay S, whichcircuit is closed when the connector wipers reach the marked line. Theconnector is stepped until its wiper D is brought to the marked contactwhereupon the following circuit is closed 1 earth over contact a l,wiper DT3 and its bank contact, one of the wipers DIE-6 depending on theposition of switch DT, wire 11, bank contact and wiper D of theconnector, bank contact and wiper 8 0t CCF in position 2, contact 63,relay S, winding I, to battery. Relay S operates and at contact .93opens the stepping circuit of the connector magnet. At contact cl relayS locks up over its winding II and contact 7)? to earth and opens thecircuit oi relay G. Contact 82 closes the circuit for test relay 1? overwiper 6 of CCli and wiper C of the connector. A test of the called lineis now made duringthe release period of relay G, the circuit being fromearth over contacts g3, 82, windings I and II of relay P, wiper6 of CCF,wiper C of CS, contact Zal, (Fig. 7), relay CO to battery. It the linebe free relay P operates and short circuits its high resistance windingI over contacts )1 and b1 and connects earth thereover for holding bymeans of its winding II and for reducing the potential of the test bankcontact in the connector to mark the line engaged. Contact pet closesenergizingniagnet DB of switch :CCF a Consequent on the release ofrelayG which now takes place, contact 96 opensthe circuit of magnet DFwhichreleases and steps switch CCF to its third position. Relay Ereleases consequent on the opening of contact g2 and at contacts 02 and63, a circuit is closed for ringing the called subscriber. This circuitis over the ringing generator RC, contacts Wt, 392, 63, wiper 8 of CCFin position 3,contact ce l in the connecting circuit, connector wiper B,the called loop, Wiper A of the connector, contact @423, wiperr of CCF,contacts as, Z3, 62, p5, r5, winding I of relay'TR to battery.Atthefsame time a ringing signal is transmitted to the callingsubscriber over Wire RS, contacts T8, 193, (Z6, Z2, a3, 62 and wiper lof CCF.

When the called subscriber replies relay TR operates by means of itswinding I in the above-traced circuit andflocks up over its winding IIand contacts M1 in series with relay Q, winding II, contact '04 toearth. Contacts W3 and g6 connect battery over contacts jtQ and s6,wiper 4 0i? CF and D of CF, subscribers meter M (Fig. 2) to earth andthe call is metered against the calling subscriber. Contacts 2W2 and 91open in the circuit of relay ST and contacts W4 and g5 connect earthover wiper 2 of CCF to relay VV in the connecting circuit to operate it.At contacts col-wed the speaking circuit is switched through and currentis fed to the calling lineover relay YA and to the called lineoverrelayYY and the register controller is disconnected from the called lineside of the feeding bridge. Contacts @115 and 0126 connect earth to thetest Wipers of the call finder and connector respectively of the connecting circuit, the latter contact short circuiting relay P, andcontact oo7 opens the holding circuit of relay TC. Relays YA and YYoperate and close a holding circuit for relay VV and contactyyQ connectsearth to Wiper D of CF and conversation ensues.

onsequent on the release of relay TCby the opening of contact m7 relayAin the register controller releases followed shortly by relay V. IVhenrelay V releases, earth over the front of contacted is disconnected andrelays TR and Q, releases slowly. Relay B is released at contact '05,relay TP at contact o3 andrelay SA at contact o2. Relay S is released atcontact Z27 and contacts 52 and 53 open further points in the circuit ofrelay A. Over the back of contact we a circuitv is-closed'for drivingthe digit switches to their normal positions. The units switch is firstrestored, its magnet DU selfstepping in a circuit includingself-interrupting contact du, wiper DUl and contact '04 and when thisswitch reaches its normal position its stepping circuit is opened and asimilar circuit for switch DT is closedover wiper DTl and normal contactin the bank of wiper DUl, the circuit being opened when the tens switchreaches, its normal position.-. When this occursthe circuit of relay STis closed at wiper DT5 and all'the other, relays having 7 released, theregister controller is free for use The line testsbusy so long as thiscondition persists by the disconnection of the connector.

test circuit at contact Zal whilst battery over relay CO and contactsZal and p92 operates a high resistance relay foristarting a delayedalarm device. 7

It When the called line is tested, itis found busy relay P does notoperate and on the release of relay G,ja busy signal is transmitted tothe calling subscriber over. wire BS, contacts 84, g5, p3, (Z6, Z2,123,62 and wiper 1 of CCF. V v

It will nowbe assumed that an individual line subscriber-wishesto make acall to another subscriber who is one of a number connected to a partyline, The numbers, of party line subscribers contain 3 digits, the firsttwo digits representing vthe linein the exchangenumbering scheme, thethird digit being a digit forthe selection ofthe appropriate ringingcode for calling the party desired. The first digit of party linesubscribersis 4 and contact a in the bank of wiper DT6 is connectedtowiper DU8, contacts of which associated with party lines are commonedand connected to relay R which brings about circuit changes forpreventing the connection of ringing current after the end of the secondimpulse train andfor the selection of-the' appropriate ringing code. a K

,The call proceeds in the manner above described until the end of thesecond train of impulses. The tens digit switchhas been set tothe fourthcontact in its banks and the tact,.wiper DT8,.commoned contacts to.relay contact rcZl by which it holds during the subsequent impulsetrain. Contact 12 prepares a circuit for magnet DA of the code select- 7ing switch. Contact 14 disconnects theringing generator which providesthe interrupted ringing current for ordinary subscribers lines andprepares a circuit for the application to thefcalled line of coderinging current; contact r3 disconnects the. ordinary ringing signalcircuit over wire RS. Contact r5 disconnects relay TR from the ringingcircuit and closes an alternativeureturn circuitfor the ringing current.Contact r6 opens the circuit of relay E untillthe third trainof impulsesis dialled thereby preventing the. stepping of the connector should thecalling subscriber delay or omit to dial the third digit. The receipt ofthe third digit by relay A is repeated to magnet DA in the followingcircuit :.earth over contacts a2, '06, 034, MM, 7 2, magnet DA tobattery. Contact a3. holds relay RD during the receipt of the impulsetrain. Switch DA is provided with 6 wipers and corresponding banks ofwhich wipers DAQ and DA3 are directly concerned with the ringing of theparticular party required. The. bank contacts of wiper DA3 are connectedto" wipers DB2DB6 of a' switchDB to which reference will shortly be.made whilst the even contacts'of wiper DA2 are commoned and connectedto certain contacts in banks DB26.and to relay RR, the wiper DAQ itselfbeing connected to certain other contacts in the banks of switch DBprior to-those which determine the end of a ringing code period. t I

7 When switch DAis steppedfrom its normal position relay E isre-operated, and closes the circuit for the connector driving magnetwhich steps the connector to the contacts of the required line markedover wiper DT'3 and oneof the wipers DU2-6 and the usualtest is made...On the-release of relay RD at the end of the third digit and assuming.for the'moment the line to be free, an interrupter isc-onnected overcontacts n5 and rcZ2,.wiper cZa-5, front contact p6 of the test relay P,magnet DB to battery. Magnet DB is energized intermittently to step thewipers DB16 and after a few steps a circuit is closed. from earth overcontact 1'd3, wiper DA3, one of the wipers DB26, relay RR to battery.This is thecommencementof thecode ringing period. Relay RR operates andat contact W1 connects the continuous ringinggenerator over frontcontact R4 and wiper 8 of CCF in position 3 to the called line whilecontact W2 connects a tone over wire DS.'COIlt-1CtS 723, (Z6, Z2, n3,wiper 1 of CCF to the calling line to provide a ringing signal similarto the code to be transmitted.

As switch DB is stepped, relay RR is intermittently operated dependingon its connections to the bank oi switch DB and the particular bank ofthat switch in use. It will is noticed that each wiper of the set DB2-6is connected to consecutive pairs of contacts in the bank of wiper DA3so that as far as this wiper is concerned the same code would be sentout for two positions of the code selecting switch DA. However, in orderto distinguish between the digits represented by a pair of contacts inthe bank of wiper DA3, a wiper DAQ and bank are employed, the evencontacts only in this bank being utilized. ll iper DA?) is connected tocontacts in the banks of switch DB immediately before these whichdetermine the end of the code and the comnioned even contacts areconnected to relay RR so that for even third digits, an extra ring isincluded in the code. When the whole code has been transmitted, switch Bis: stepped on to the cominoned contacts in the latter part of its bankcon nected to relay RT which thereupon operates and remains operateduntil the switch reaches its normal position. A circuit is now preparedtor relay TR as follows :earth, winding 1 of relay T 1, contacts M2, r5,5, 62, Z3, wiper of CUF in position 3, contact on3, the called linewires, contact 10%}, wiper 8 of GOP, contacts 63,122, rel, rrl, will, tobattery. This circuit is prepared at the end of each code ringing periodand when the subscriber replies to the call relay TR operates and locksup and in conjunction with relay Q; brings about the switching throughof the connection. Contact cs6 short circuits relay P which releases andat contact p6 opens the stepping circuits of switch DB and closes acircuit for its rapid return to normal should not have reached tiisposition. In the normal position of switch DB1 a homing circuit forswitch DA is prepared.

Following on the switching through of the connection, the registercontroller is released and on the release of relay V the Funits and tensdigit switches are restored in turn.

The disconnection of earth over front contact he releases relay 1t andthehoming circuit for switch DAis closed over contact r2,selfinterrupting contact do, wipers Bill and D131, and switch DA isstepped to its normal position. The register controller circuits are nowall in their normal conditions and the apparatus may again be taken intouse.

H the called line is busy when tested relay P does not operate andswitch DB is not stepped so that ringing current is not applied to theline. The calling subscriber receives busy signal as in the case of acall to a busy individual line.

l'Vhen a call is orignated by a party line subscriber the procedure issimilar to that de scribed for a call by an individual subscriber.

It a party line subscriber desires to call another party on the sameline, he proceeds as tollows:- t

On removing the'receiver from its hook and on receipt. of the diallingsignal, the subscriberdials the digit 7, after which, and with thereceiver still oil, he uses the hand magneto generator provided with theinstrument for calling the party required, manipulating it seas to applyringing current on to the line in accordance with the code of therequired subscriber.

When the receiver. is first lifted, a free register controller at theautomatic exchange is taken into use and the dialling signal isconnected to the calling line when it has been found by the call finderCF. Thedigit 7 is received by relay A and switch DT is stepped to itsseventh bankcontact. At the end of the impulse train, relay Dreleasesand earth over contacts 414 and (Z5 and wiper DT6 is connectedto relay RL, which thereupon operates and locks up over contact 1%independently of switch DT. Contact rZl connects battery over a highresistance and wiper 4 of GOP to wire 05 in the line circuit which inthe case of a party line has an auxiliary equipment as before mentionedconnectedbetween it and the main distributing frame. A relay in thisequipment connects earth to wire 0 to hold relays CO and PG operated andto disconnect the line circuit from the assigner andto mark the lineengaged in the connector multiple, this earth connection being extendedover contact 001 to the test bank contacts in the call finders. ContactrZ2 opens the holding circuitot relay B which in turn releases relays Aand V and the register controller circuits are restored to their normalcondition. The engaged marking is maintained for the duration of thecall and is controlled by the auxiliary equipment referred to. When bothparties replace their receivers, this earth is removed, relays CO and PGrelease and the line circuit reverts to its normal condition. It may benoted that although relay PG is operated, there isno circuit overcontact 1092 to the alarm relay circuit due to relay LA beingunoperated.

Thesystem provides forthe connection of small private branchexchangesand those are called in the same manner as an individual line bydialling the number of the first of the group oflines connected to theP. B. X. If this line be busy, the connector proceeds to hunt over theP. B. X. group in search oi a tree line. In order that allthe lines of aP. B. Qshall be marked when a call to one ismade, the appropriate bankcontacts of switch DU are conimoned and the corresponding marking wires11 are connected to the bank contacts of wiper D of the connector over abreak contact jig 3 shown in Fig, 7, the dotted line connection beingremoved except in the case of the last line oi the group when the strapis retained, as whatever the condithe markin tion of the last line ofthe group, the con nector must be stopped thereon. As the operation ofthe connector is that of a hunting switch searching for a marked line,it will be realized that switch CS willflbe. stepped until a marked lineis reached. If any of the lines of the group other thanthe last arebusy, the marking in the bank of wiper D of the connector will not bepresent owing to circuit being open at contact 3993, relay G beingoperated consequent on the operation of the cuteofi' relay CO, and theconnector will be stepped on until a marked contact isreached. Shouldall the .linesof a P. B. X. group be busy, the connector is stopped onthe last contact of the group as this contact is always marked, thecontact 1293 of the line circuit being short circuited.

by the strap. 7

If any group often lines is. not connected, such asthe groups havingfirst digits 1 and 8 in the-present example, the corresponding contactin the bank of wiper DTG is connected to a relay L." If any. individualline 2' in a group is not connected, the corresponding contacts in thebank of wiper C of the connectors, are connected towire 13 which is alsoconnected to relay L in the register controller when relay E isoperated. If, now,

either the digit 1 or 8 be dialled as the tens digit, relayL operates bymeans of its winding I on the release of relay D and locks up overcontacts Z1 and 124. Contact Z4 opens preventing operation of relay E,and contact Z2 connects a distinctive tone signal over wire NU, contactas, wiper 1 of CCF to the calling line to notify the calling subscriberthat he has called a dead number. Should the tens digit be correct, butthe whole number represent a dead line, relay L is not connectedover-wiper DTG. 'At the end of the second train of impulses, relay Eopcrates and at contact 66 battery over winding II of relay L isconn'ectedvia wire 13 to the multipled contacts in the bank of wiper Cof the connector, the usual marking circuit being completed over wire11. When the marked line is reached, relay S operates and connects relayP in the test circuit, but owing to the high resistance of windings IIof relay L, relay P does not operate but relay L does. Contact Z1 closesa locking circuit over winding I of relayLv and contact Z8 opens inthestepping circuit of the connector while switchCCF is in'its secondposition.

The distinctive toneis connected to the calling line at contact Z2.

Consideration will now be given to calls,

made over a junction between the automatic exchange and a manualoperator at a main exchange. The auxiliary equipment shown in Fig. 1 isconnected'between the junctionterminals on the main distributing frameand'the line circuit, Fig. 2, and Fig. 1 must be assumed to be nowconnected-to the. left of thefline circuit shown in Fig. 2. The strapconnecting wire 01 from. the connector multiple and wire. 0 from relayCO is disco-n.- nected and meter .M is disconnected from wire (Z in Fig.2. ires 0 and 01 are now joined through the low resistance winding I ofrelay JS and wire 61 is connected to winding II of relay JS. in theauxiliary equipment.

There may be junctions to only one main I In thefirst exchange or tomore than one. case, a subscriber Wishing to make a call over ajunction, dialsthesingle digit 0. In the second case he dials the digit0 followed by anotherdigit signifying the particular group of junctionsrequired. As re- 'gards the connector circuit, arrangements the markingbank of the connector in a manner similar to the described for P. B. X.lines. lVhen there is more than one junction group, the tenthcontact inthe bank of wiper DT3 is disconnected fromwire' 12 and connected to oneof the wipers DU26 depending on the tens group in which it is desired toconnect the junctions.

When there is only one group of'junctions, a subscriber wishing to makea call over a junction dials thesingle digit 0 and at the end of theimpulse train relay J T operates over its winding I and wiper DTG. RelayG operates and earth over contacts 414:, a1, 92, n1, front contact jtl,contacts .cZ3,'Z4,. wires 6,

contact T6, is extended to relay E- which thereupon operates instead. ofawaiting the end of a second train of impulses. The strap across backcontact y'tl shown in dotted lines is removed sothat relay vD does notre-operateon the closure of contact 92.

. 1. Consequent on the operation of relayE the connector is stepped insearch of a free junction and when one 1s found, relay S operates viathe connector marking bank, Wire 12, and.

wiper DT3. Relay P operates over Wiper C ofthe connector, winding I ofrelay J S (Fig. 1) and relay CO in the line-circuit and switch CCF isstepped to itsthird position where ringing current is appliedto thejunction;

Relays J Sand CO operate, the latter extending earth first over the lowresistance wind-' ing of relay P and later over contact @126, theconnector wiper C and bank contact, contacts Zal and 001 in the-linecircuit to the .testbank contacts of the call finders to mark the lineengaged in the fall finder banks. Relay JR operates but neither it norrelay JS serve any useful function at this stage. On the operation ofrelay JT contact jtz? opens the metering circuit to prevent metering onjunction calls and prepares a locking circuit for winding 11 of relay JT when the operator replies to the call. At the end of the conversationwhen the calling subscriber replaces his receiver, relays YA and VV inthe connecting circuit G release and contact @126 opens the circuit ofrelay J S releasingit and relay GG. Relay LA is re-connected to thejunction in the line circuit and during the release period of relay JR,the current in the junction is reversed thereby giving a clearing signalto the operator.

If there is more than one junction group, the back contact jtl is shortcircuited by the strap shown in dotted lines and the connec tion of thetenth contact in the bank of wiper DT3 is made as above described. Thesubscriber dials the requisite digits to reach the exchange desired andat the end of the first train, relay D releases and operates relay J T.At the same time relay Gr operates and on the closure of contact 5/2relay D re-operates over normal contact and wiper BUT, the strap acrossthe back of contact y'tl, contacts n1, g2, a1, and o l, and opens thecircuit of relay E before this relay has time to operate in a circuitincluding the front of contact 61. The second digit is now dialled andat the end of the impulse train, relay ltl ope ates and search for ajunction in the marked group by the connector takes place.

Consideration will now be' given to calls made by a manual operator overthe junc tion to a subscriber on the automatic eX- change, after whichthe various special services available only to an operator will be dealtwith.

An operator at the main exchange desiring to make a call to theautomatic exchange inserts a calling plug into the junction jack therebyoperating relay LA overa loop closed in the cord circuit. The assignerallots a free register controller to deal with the call and the registercontroller hunts for and seizes a free connecting circuit and theassociated call finder is rotated in search of the calling unction. Whenthis is found the register controller and switch GOP is stepped from itsfirst to its second position. Relay B operates when the junction isfound and a circuit is now closed from earth over contact Z71, windinglof relay J G, contacts t02, r11, 86, wiper l of GGF, wiper D of the calltinder, wire of winding II of relay J S to battery. Relay J G which isof high resistance operates but relay J S does not. At contact jol alocking circuit is prepared for winding 11 of relay J G, this circuitbeing closed on receipt of the first impulse of the tens digit train. Itwill be noted that relay JG can only operate on calls made by anoperator over a junction as in the case of subscriber initiated calls,Wire dis earthed over the meter M. The operator receiver dialling signaland the connection is set up in the manner described for calls made by asubscribe When the called subscriber replies relay YY operates and atcontact g g/Q connects a comparatively low resistance earth to Wiper D01' the call finder and rela J S operates. Contact jsl operates relay Rto prepare for the giving of the ring-oil signal. When the calledsubscriber clears relay YY releases and aticontact yg/Q releases relay JContact jsl opens the circuit of relay JR, but this relay being slow torelease a period occurs when with relay J S released and relay JRoperated, a reversal of current in the junction Wires takes placewhich-operates the clearing indicator at the main exchange. Current iscut oil the junction on the subsequent release of relay VV. 7

If the operator wishes to Offer a trunk call to an engaged subscriber,the junction is eX- tended through a free connecting circuit to aregister controller and relay JG is operated. Contact 7'03 disconnectsrelay JT and pre pares a circuit for relay TO. a

The operator on receiving dialling signal dials the directory number ofthe wanted subscriber prefixed by the digit 0. At the end of the lastimpulse of the first train of impulses representing the digit 0, relayTO operates over wiper DTG and locks up over its contacttol and contactat, and relay JG locks up over. its winding II and wiper DT2, thecircuit over its winding I being opened at contact $02. Gontact 2605opens the dialling signal circuit. A circuit is now closed from earthover contacts jc2,.t03,wiper DUl and normal contact, wiper DTl andcommoned contacts, self-interrupting contact (it, magnet DT to battery.Switch DT self-steps to normal whereupon thelocking circuit of relay JGis opened at wiper DT2. Relay TO remains held. The remaining digitsrepresenting the subscribers directory number are now dialled and theconnectorsearches for the line marked in itsmarking bank. l/Vhen this isreached relay S operates and the test circuit is closed at contact 82 inthe usual Way. At the same time, relay VV in the connecting circuit isoperated from earthover contacts 85 and 2504, and wiper 2 ofGGF inposition 2. Contact @126 short circuitsrelay Pancl relay TG is releasedatcontact/vo7 thereby initiating release of the register controller. Theconnection is switched through and as the called subscriber is alreadyengaged in a connection, relay YY will operate round the loop which isalready closed. The operator can speak to the wanted party and requesthim to clear the connection and await the offered trunk call. Contact y2 operates relay J S and when the Wanted party clears, a clearing signalis received by the operator. .She then clears the connection in order torelease If-the operator desires tofascertain whether a fault exists inthe automatic exchange or, if a fault has been previously signalled,whether it still persists, she dials the single digit 9; The registercontroller being taken into useby an operator, relay JG is operated andat contact 3'04 relay N is connected to the ninth contact in'the bank ofwiper DT6 in place of relay L. At the endof the impulse train "relay Noperates and at contact n3 connects the fault tone lead FT over wiperDA6 and normal contacts at each end of its bank, and wiper 1 of CGF tothe line so that the operator receives a tone denoting the type of.fault existing, assuming there to be one.

It may be noted that should a'subscriber ,dial. 9 as a first digit,relay L will operate over wiper DTG, bank contact 9 andlback contact jal and he will receive the dead number tone.

By dialling certain numbers, the operator can control the charging ofthe battery at the automatic exchange and ascertain by means of a tonesignal the state of charge of the battery. This being another serviceavailable to operators only, its operation is made deanypossible-stepping of switch DB. The

second train comprising 3, 5 or 7 impulses is dialled and is repeated ina circuit from earth over contacts a2, o6, (MEWZA Q to magnet DA andswitch DA isstepped accordingly. 'At-the end of the impulse train, relayRD which is held duringimpulsing overcontacts a3 and Tell, releasesandwinding-III of relay D is connected over contacts r0l5 and net andwiper DA6 to the appropriate lead. Ifthe second digit is 3 a tone istransmitted over the leadconnected to contact 3 in the bank of wiper DAGtowinding III of relay A and the tone is induced in the windings I andII of thisrelay and thence over the junction to the operators position.If the second digit be 5? or 7 earth over winding III of relay Aoperates the relay to effect the re quired operation. Relay A is notheld by this winding owing tothe resistance of the circuit in whichit isincluded. The register controller is released by the withdrawal oftheplug from the junction jack by the operator.

Briefre-ference-will now-be made to the arrangements provided forreleasing the register controller if it is not otherwise released withina prescribed time. 1 I

Vhen the register controller is taken into use relay ST'operates and atcontact st3closes a circuit forrrelay TP, the circuit being maintainedafter the calling line has been found by the call finderby contact '03.Relay TBoperates and star-ts up a timing device and earth isconnected towire 14, thence over contacts ml and 122 to relay SA. Relay SA operatesand locks up over contact sal and at contact -sa2'conn'ects relay ZA towire-15. After the elapseof a prescribed'time interval and if relay Vhas not yet been released earth is If a-fault develops on a subscribersline or a subscriber fails to clear after aconversation, or his line isotherwise looped, relay CO is released either by relay: VV in theconnecting circuit or by the forced release of the register controllerand relayLA re-operating, relay 'PG- remains held. A circuit is thenclosed from battery over relay CO, contactslal and 1292 for relay PLwhich is of high enough resistance to prevent operation of'relay CO andafter the elapse of a prescribed interval, an alarm'relay is operated.The operated condition of this relay may be ascertained by means of atone signal connected to a junction in consequence of an operatordialling the digit 9 to ascertain ifa' fault exists. I

WVhat is claimed is: I

.1. t In a register controller arranged to control the setting ofautomaticswitching apparat-us by the application of a marking potentialto one of a plurality of marking conductors, marking conductors dividedinto groups, a register operable in accordance with a digit of atelephone number to select a marking conductor ineacli of said groups,and a register operated in accordance with a dilf'erent digit in thetelephone number to select a particul ar one of the markingcondu ctorsselected in accordance withthe firstnamed 2. In a telephone systemwherein automatic switchesare guided into connection ductors, and meansfor preventing the marking of a conductor by one register controller ata time when a conductor is marked by the other register controller.

In a telephone system, two register controllers, a plurality ofconnector switches having access to called lines, means for extending aconnection from a calling line to one of said connector switches and forrendering one of said register controllers temporarily individual tosuch connector switch, means controlled over any one of a plurality "ofmarking conductors for operating said connector switch as a finder tofind a called line, means including registering apparatus in theregister controller set over the calling line to mark one of saidconductors, and means for preventing the marking of one of saidconductors by one of said register controllers at a time when aconductor is marked by the other register controller.

a. In a telephone system, a trunk line, a plurality of registercontrollers, means for completing a connection between a calling lineand said trunk line and for rendering one of said register controllerstemporarily individual to said trunk line, means including registeringapparatus in the register controller for recording the number of the de'sired line and for recording the designation of the desired party on theline in case a party line is called, automatic switching mechanismcontrolled in accordance with the setting of said registering apparatusto ex tend a connection from said trunk line to the desired line, andmeans including a ringing-code generator individual to said regis tercontroller to generate and transmit to the called line the particularcode of the called party as indicated by the setting of the saidregistering apparatus.

In a party-line telephone system, a code generator comprising aplurality of codegenerating devices for generating separate codescorresponding to different parties on a party line, a digit registerhaving access to said code generating devices and arranged to select thesame device upon the registration oi either of two digits, and meansassociated with said registering device for mak ing an addition to theselected code automatically when it is set in one of the two saidpositions.

6. In a party-line telephone system, a code generator comprising aplurality of codegenerating devices for generating separate codescorresponding to different parties on a party line, a digit registerhaving access to said code-generating devices and arranged to select thesame device upon the registration of either of two digits, and meansassociated with said registering device for automatically modifying theselected code when it is set in one of said two positions.

7. In an automatic telephone system, an

automatic hunting switch having access to lines, means for extending aconnection r'rom a calling line to said switch, means includingregistering apparatus set over the calling line in accordance with thedestination of the call for marking a group oflines accessible to saidswitch, means for automatically causing said switch to advance to themarked group of lines, and meanscontrolled by the busy or idle conditionof the lines within thegroup for continuing the hunting movement of saidswitch until an idle line is encountered.

8. In a telephone systeim'an automatic switchhaving access to lines,atest contact for each line, a marking contact for each line, meansincluding registering apparatus for marking one of said markingcontacts,means for operating said switch into engagement with the marked contact,and means controlled over the associated test contact for continuing themovement of the switch in case the line associated with the markedcontact is busy; 1 a

9. Ina telephone system, a manual switchboard, another switchboard,aline extending between said switchboards, means for setting up aconnection over said line through said switchboardsand for setting up acurrent flow over said line, means for breaking down said connection atthe said other switchboard, and means thereupon effective formomentarily reversing the current flow over said line. Y I p 10. In atelephone system, means including automatic switching apparatus forsetting upconnections to subscribers lines responsive to impulsesrepresenting the digits in the telephone numbers of said lines, meansincluded in said automatic switching appa ratus for denying theconnection in case the called line is busy, and means for causing theconnection to be completed to a busy line in case a preassigned digit isprefixed to the subscribers number.

11. In an automatic telephone system, automatic switching apparatus forthe common use of operators and calling subscribers to set upconnections to called lines, means for denying the connection in case acalled line is busy, and means responsive only in case the call is beingset up from an operators switchboard for completing a connection to abusy line responsive to prefixing a preassigned digit to the digits ofthe telephone number.

12. In a telephone system, a switch controlling device comprisingregistering apparatus for registering the tens and units digits incalled numbers, said registering apparatus having one movement for thetens digit and another movement for the units digit, and means forcausing said apparatus to operate twice in its tens digit movement incase the first digit received by such apparatus is a predetermineddigit, the last named means inl siing ang me t tom ti lly r leasing saidapparatus at the end of the said predetermined digit. 7

a 13. In a'telephone system, a telephone ex.-

change including automatic switches and reg ster controllers arranged tobe set n accordance with desired numbers to'control said switches, aline incoming to said exchange,.means 1n said exchange for givingsignals indicative roflconditions Withinthfe exchange, and meansincluding said register controllers for extend ng the incoming l ne intoassoclation with the=last named means,

whereby the conditions existing in the ex- [which said registers areoperated, means change maybe determined over said line.

14. In a register controller for use in con.- trolling the operation ofautomatic switches in an automatic telephone exchange, a tens register,a units register, and a party register arranged to be operated toregister the tens, units, and party selecting digits in a telephonenumber, an impulsing circuit over automatically etfective for shiftingsaid impnlsing circuit from the tens register to the units register andfor later switching it from the uni-ts register to the party register,and a means responsive to said tens register being set in apredetermined position for there-- upon switching the impulse circuitdirectly from the tens register to the party selector.

15. In telephone system, three registering. devices arranged to respondsuccessively to three digits, and means responsive to the setting of thefirstregister in accordance With a predetermined digit for causing thethird register to respond to the second digit. lnwitness whereof, Ihereunto subscribe name t i 2 t ay f ebr ry, A- D.-

CHARLES LEONARD PETERS. Y

.eo v

